I can't put my finger on why this game is so compelling, but it certainly is. That little, pixelated tombstone that appears when you die---ah, so perfect.

I think the food mechanic adds a lot. Every step costs you, so every step counts.... and when you're out of food, and there's no food in sight (so your HP decrease by one per step), the tension is incredibly high.

I once died from starvation a single step away from food. High drama, that. Like the guy crawling through the desert gasping "water, water" who finally passes out with the tips of his fingers in the oasis.